Is Warfarin safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Warfarin. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
No decreases in vitamin K-dependent clotting factors or bleeding occurred in 2 infants who were breastfed for 56 and 131 days, respectively, during maternal anticoagulation with warfarin.[ 4 ] In one telephone follow-up study, mothers taking warfarin reported no adverse effects among 5 breastfed infants.[ 6 ] A mother had been taking warfarin 5 mg daily for the first 7 weeks postpartum for a pulmonary embolism. At this time, she began taking 25 mg daily by mistake and took this dose for 7 days. Upon presentation to the emergency room, her INR was greater than 10 (usual therapeutic maximum 3.5), her prothrombin time was greater than 100 seconds (normal up to 11.2 seconds), and her aPTT was 62.5 seconds (normal up to 32.7 seconds). She had been nearly exclusively breastfeeding her infant since birth. Her 8-week-old infant was healthy with an INR of 1.0, prothrombin time of 10.3 seconds, and a slightly elevated aPTT 33.8 seconds. However, 3 weeks previously, the infant's aPTT was 38.9 seconds, so the elevated aPTT was judged not to be caused by warfarin.[ 7 ]
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Maternal Levels. Warfarin was not detected ( 25 mcg/L) at 4 hours after a dose in the breastmilk of 13 mothers who were 3 to 12 days postpartum and anticoagulated with warfarin in doses of 2 to12 mg daily in one study.[ 4 ] Warfarin activity was also not detected in the milk of 2 anticoagulated women (warfarin dose unspecified).[ 5 ] Infant Levels. No warfarin activity was detected in the plasma of any of 7 infants in whom it was measured. Measures of anticoagulation were within normal limits in all infants tested.[ 5 ]
Alternatives LactMed lists
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.